Trail Brake demonstration to HPDE-1 student turns into a live classroom. NASA HPDE-4 SPR-M 

At 1:23, I reached down at mid corner and turned up the boost - 1st of 3 clicks. Was that 100 mph down the Turn 4 chute in a hatchback? That is GT3 speeds!
Track: Summit Point Main
Car: Subaru STi Hatch
Tires: Toyo RR 255/35-18
Driver: NASA Sr. Instructor/Coach
Entering Turn 1 off-line requires several advanced skills to be executed precisely. Downshift/Rev-Matching, Heel/Toe, and Trail Braking are the foundation skills. Left Foot braking is an optional advanced skill.